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   Dendroctonus valens (insect)
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    Details of this species in United States (USA)
    Status: Native
    Invasiveness: Not specified
    Occurrence: Established
    Source: Cognato 2003
    Arrival Date:
    Species Notes for this Location:
    Dead or dying Pinus, Picea and Abies are hosts for D. valens in its native North America. Healthy trees are occasionally killed too (Cognato 2003). The most common bark beetle species infesting pines in urban landscapes and at the wildland-urban interface in California are the engraver beetle, the red turpentine beetle and the western pine beetle (Seybold Paine & Dreistadt 2008).
    Reports indicate that bark beetle populations tend to increase following fire and tree thinning. Higher release rates of host volatiles, including pine monoterpenes, may explain such increases in activity of D. valens and other bark beetles (Furniss and Carolin 1977, in Erbilgin et al. 2007, for a conflicting report see: Wallin et al. 2008).
    Management Notes for this Location:
    The red turpentine beetle attacks trees wounded or stressed by construction activities (eg: paving, grading or trenching). It has been suggested that damage from the beetle can be prevented by not conducting these activities within 15 meters of large pines.
    Inspection of trees for signs of the beetle are made via inspection for pitch tubes. A few pitch tubes on an otherwise healthy tree or old pitch tubes that are hardened and yellowed are generally not cause for concern. In vigorous trees the flow of resin apparently prevents egg-laying. Beetles may remain in these trees expanding their galleries laterally or vertically but they seldom deposit eggs. The appearance of five or more new pitch tubes over a couple of months warrants more careful inspection. Injury, disease, or attacks by other bark beetles are likely causes for repeated red turpentine beetle attacks. A tree that exhibits symptoms of stress and has many red turpentine beetle attacks is at high risk for mortality (Randall 2006).

    Because the red turpentine beetle lives in a protected micro-habitat beneath the pine bark insecticides are not usually effective. Chemical spray applications made once the beetles have aggregated and penetrated the bark is ineffective. Treatment must target beetles during their flight activity preventing beetle attacking a new host tree. The bark of the tree is sprayed so that when the beetle lands on the pine to bore it is killed. Spraying a persistent insecticide on valuable uninfested pine at risk of infestation be warranted.
    Protective spraying for bark beetles must be done by a licensed pesticide applicator. Pyrethroids (such as Astro or Dragnet) or any of the flowable (EC) formulations of carbaryl may be applied to protect healthy trees from bark beetle infestations. In most cases, the time to apply is in late winter to early spring in warm lowland areas.
    Infested tree or tree limbs may be removed and chipped or burned. General hygeine principles should be followed. For example stumps of infested trees provide optimum breeding grounds for the red turpentine beetle and should be extracted and disposed of sensibly. No infested material should be piled next to, or anywhere near, a suceptible pine tree.
    Only pine species adapted to a habitat should be planted. If bark beetles are a threat only non-host trees should be planted. In North America, appropriate species would include redwoods or atlas cedars. A mixture of tree species in planted landscapes will reduce mortality resulting from bark beetles and wood borers. Stresses placed on trees caused by poor planting, planting at the wrong time of year or lack of proper care afterwards will increase a tree’s susceptibility to bark beetles or wood borers. (Seybold, Paine & Dreistadt 2008)

    Location Notes:
    Ecosystem change: Declining red pine Pinus resinosa (Aitman) stands in the Great Lakes region appears to be due to both biotic and abiotic factors. Erbilgin, Nadir and Raffa (2002) found declining stands were found to have more lower-stem-infesting bark beetles, including D. valens and weevils Pissodes species. Klepzig and colleagues (1991) found that populations of D. valens were higher in declining than in healthy stands. The presence of the bark beetle does not mean it is the cause of pine tree decline as it is possible that the beetles are simply opportunistic secondary feeders (Erbilgin, Nadir and Raffa 2002).
    Last Modified: 16/02/2009 3:34:24 p.m.

ISSG Landcare Research NBII IUCN University of Auckland